diff --git a/packages/ui/package.json b/packages/ui/package.json
index 536dea50e..39336676e 100644
--- a/packages/ui/package.json
+++ b/packages/ui/package.json
@@ -63,6 +63,7 @@
     "react-string-replace": "^1.0.0",
     "react-timer-hook": "^3.0.5",
     "stylelint": "^14.8.2",
+    "superstruct": "^0.16.0",
     "typescript": "^4.6.2",
     "use-debounced-loader": "^0.1.1"
   },
@@ -72,8 +73,7 @@
   "eslintConfig": {
     "extends": "@silverhand/react",
     "rules": {
-      "complexity": "off",
-      "no-restricted-syntax": "off"
+      "complexity": "off"
     }
   },
   "stylelint": {
diff --git a/packages/ui/src/containers/SocialSignIn/SocialSignInDropdown/index.tsx b/packages/ui/src/containers/SocialSignIn/SocialSignInDropdown/index.tsx
index 19b94f404..1c2d3dc00 100644
--- a/packages/ui/src/containers/SocialSignIn/SocialSignInDropdown/index.tsx
+++ b/packages/ui/src/containers/SocialSignIn/SocialSignInDropdown/index.tsx
@@ -5,6 +5,7 @@ import { useTranslation } from 'react-i18next';
 import Dropdown, { DropdownItem } from '@/components/Dropdown';
 import useSocial from '@/hooks/use-social';
 import { ConnectorData } from '@/types';
+import { isKeyOf } from '@/utils';
 
 import * as styles from './index.module.scss';
 
@@ -47,8 +48,7 @@ const SocialSignInDropdown = ({ isOpen, onClose, connectors, anchorRef }: Props)
     >
       {connectors.map((connector) => {
         const { id, name, logo, logoDark } = connector;
-        const languageKey = Object.keys(name).find((key) => key === language) ?? 'en';
-        const localName = name[languageKey as Language];
+        const localName = isKeyOf(language, name) ? name[language] : name[Language.English];
 
         return (
           <DropdownItem
diff --git a/packages/ui/src/hooks/use-bind-social.ts b/packages/ui/src/hooks/use-bind-social.ts
index a296d654e..138820b0a 100644
--- a/packages/ui/src/hooks/use-bind-social.ts
+++ b/packages/ui/src/hooks/use-bind-social.ts
@@ -1,18 +1,16 @@
-import { Optional } from '@silverhand/essentials';
+import { conditional } from '@silverhand/essentials';
 import { useCallback, useEffect, useContext, useMemo } from 'react';
 import { useLocation } from 'react-router-dom';
+import { is } from 'superstruct';
 
 import { registerWithSocial, bindSocialRelatedUser } from '@/apis/social';
 import useApi from '@/hooks/use-api';
 import { PageContext } from '@/hooks/use-page-context';
 import { LocalSignInMethod } from '@/types';
-
-type LocationState = {
-  relatedUser?: string;
-};
+import { bindSocialStateGuard } from '@/types/guard';
 
 const useBindSocial = () => {
-  const state = useLocation().state as Optional<LocationState>;
+  const { state } = useLocation();
   const { experienceSettings } = useContext(PageContext);
   const { result: registerResult, run: asyncRegisterWithSocial } = useApi(registerWithSocial);
   const { result: bindUserResult, run: asyncBindSocialRelatedUser } = useApi(bindSocialRelatedUser);
@@ -54,7 +52,7 @@ const useBindSocial = () => {
 
   return {
     localSignInMethods,
-    relatedUser: state?.relatedUser,
+    relatedUser: conditional(is(state, bindSocialStateGuard) && state.relatedUser),
     registerWithSocial: createAccountHandler,
     bindSocialRelatedUser: bindRelatedUserHandler,
   };
diff --git a/packages/ui/src/hooks/use-form.ts b/packages/ui/src/hooks/use-form.ts
index 941680588..3a0743ff1 100644
--- a/packages/ui/src/hooks/use-form.ts
+++ b/packages/ui/src/hooks/use-form.ts
@@ -1,9 +1,9 @@
 import { useState, useCallback, useEffect, useRef, FormEvent } from 'react';
 
 import { ErrorType } from '@/components/ErrorMessage';
-import { entries } from '@/utils';
+import { entries, fromEntries, Entries } from '@/utils';
 
-const useForm = <T>(initialState: T) => {
+const useForm = <T extends Record<string, unknown>>(initialState: T) => {
   type ErrorState = {
     [key in keyof T]?: ErrorType;
   };
@@ -19,12 +19,12 @@ const useForm = <T>(initialState: T) => {
   const fieldValidationsRef = useRef<FieldValidations>({});
 
   const validateForm = useCallback(() => {
-    const errors = entries(fieldValue).map<[keyof T, ErrorType | undefined]>(([key, value]) => [
+    const errors: Entries<ErrorState> = entries(fieldValue).map(([key, value]) => [
       key,
       fieldValidationsRef.current[key]?.(value),
     ]);
 
-    setFieldErrors(Object.fromEntries(errors) as ErrorState);
+    setFieldErrors(fromEntries(errors));
 
     return errors.every(([, error]) => error === undefined);
   }, [fieldValidationsRef, fieldValue]);
@@ -37,8 +37,7 @@ const useForm = <T>(initialState: T) => {
       return {
         value: fieldValue[field],
         error: fieldErrors[field],
-        onChange: ({ target }: FormEvent<HTMLInputElement>) => {
-          const { value } = target as HTMLInputElement;
+        onChange: ({ currentTarget: { value } }: FormEvent<HTMLInputElement>) => {
           setFieldValue((previous) => ({ ...previous, [field]: value }));
         },
       };
@@ -49,13 +48,13 @@ const useForm = <T>(initialState: T) => {
   // Revalidate on Input change
   useEffect(() => {
     setFieldErrors((previous) => {
-      const errors = entries(fieldValue).map<[keyof T, ErrorType | undefined]>(([key, value]) => [
+      const errors: Entries<ErrorState> = entries(fieldValue).map(([key, value]) => [
         key,
         // Only validate field with existing errors
         previous[key] && fieldValidationsRef.current[key]?.(value),
       ]);
 
-      return Object.fromEntries(errors) as ErrorState;
+      return fromEntries(errors);
     });
   }, [fieldValue, fieldValidationsRef]);
 
diff --git a/packages/ui/src/hooks/use-preview.ts b/packages/ui/src/hooks/use-preview.ts
index 9bb4a386c..506138445 100644
--- a/packages/ui/src/hooks/use-preview.ts
+++ b/packages/ui/src/hooks/use-preview.ts
@@ -1,5 +1,4 @@
-import { Language } from '@logto/phrases-ui';
-import { AppearanceMode, ConnectorPlatform } from '@logto/schemas';
+import { ConnectorPlatform } from '@logto/schemas';
 import { conditionalString } from '@silverhand/essentials';
 import i18next from 'i18next';
 import { useEffect, useState } from 'react';
@@ -7,19 +6,11 @@ import { useEffect, useState } from 'react';
 import * as styles from '@/App.module.scss';
 import { Context } from '@/hooks/use-page-context';
 import initI18n from '@/i18n/init';
-import { SignInExperienceSettingsResponse, SignInExperienceSettings, Platform } from '@/types';
+import { SignInExperienceSettings, PreviewConfig } from '@/types';
 import { parseQueryParameters } from '@/utils';
 import { getPrimarySignInMethod, getSecondarySignInMethods } from '@/utils/sign-in-experience';
 import { filterPreviewSocialConnectors } from '@/utils/social-connectors';
 
-type PreviewConfig = {
-  signInExperience: SignInExperienceSettingsResponse;
-  language: Language;
-  mode: AppearanceMode.LightMode | AppearanceMode.DarkMode;
-  platform: Platform;
-  isNative: boolean;
-};
-
 const usePreview = (context: Context): [boolean, PreviewConfig?] => {
   const [previewConfig, setPreviewConfig] = useState<PreviewConfig>();
   const { setTheme, setExperienceSettings, setPlatform } = context;
@@ -44,6 +35,8 @@ const usePreview = (context: Context): [boolean, PreviewConfig?] => {
       }
 
       if (event.data.sender === 'ac_preview') {
+        // #event.data should be guarded at the provider's side
+        // eslint-disable-next-line no-restricted-syntax
         setPreviewConfig(event.data.config as PreviewConfig);
       }
     };
diff --git a/packages/ui/src/hooks/use-social-sign-in-listener.ts b/packages/ui/src/hooks/use-social-sign-in-listener.ts
index 78733a4ea..1336903e7 100644
--- a/packages/ui/src/hooks/use-social-sign-in-listener.ts
+++ b/packages/ui/src/hooks/use-social-sign-in-listener.ts
@@ -21,9 +21,7 @@ const useSocialSignInListener = () => {
         if (parameters.connector) {
           navigate(`/social/register/${parameters.connector}`, {
             replace: true,
-            state: {
-              ...(error.data as Record<string, unknown> | undefined),
-            },
+            state: error.data,
           });
         }
       },
diff --git a/packages/ui/src/pages/Passcode/index.tsx b/packages/ui/src/pages/Passcode/index.tsx
index 5a5de9f21..a72383e88 100644
--- a/packages/ui/src/pages/Passcode/index.tsx
+++ b/packages/ui/src/pages/Passcode/index.tsx
@@ -1,13 +1,12 @@
-import { Nullable } from '@silverhand/essentials';
-import { useContext, useEffect } from 'react';
 import { useTranslation } from 'react-i18next';
 import { useParams, useLocation } from 'react-router-dom';
+import { is } from 'superstruct';
 
 import NavBar from '@/components/NavBar';
 import PasscodeValidation from '@/containers/PasscodeValidation';
-import { PageContext } from '@/hooks/use-page-context';
 import ErrorPage from '@/pages/ErrorPage';
 import { UserFlow } from '@/types';
+import { passcodeStateGuard, passcodeMethodGuard } from '@/types/guard';
 
 import * as styles from './index.module.scss';
 
@@ -16,30 +15,23 @@ type Parameters = {
   method: string;
 };
 
-type StateType = Nullable<Record<string, string>>;
-
 const Passcode = () => {
   const { t } = useTranslation();
   const { method, type } = useParams<Parameters>();
-  const state = useLocation().state as StateType;
+  const { state } = useLocation();
   const invalidType = type !== 'sign-in' && type !== 'register';
-  const invalidMethod = method !== 'email' && method !== 'sms';
-  const { setToast } = useContext(PageContext);
 
-  useEffect(() => {
-    if (method && !state?.[method]) {
-      setToast(t(method === 'email' ? 'error.invalid_email' : 'error.invalid_phone'));
-    }
-  }, [method, setToast, state, t]);
+  const invalidMethod = !is(method, passcodeMethodGuard);
+  const invalidState = !is(state, passcodeStateGuard);
 
   if (invalidType || invalidMethod) {
     return <ErrorPage />;
   }
 
-  const target = state?.[method];
+  const target = !invalidState && state[method];
 
   if (!target) {
-    return <ErrorPage />;
+    return <ErrorPage title={method === 'email' ? 'error.invalid_email' : 'error.invalid_phone'} />;
   }
 
   return (
diff --git a/packages/ui/src/types/guard.ts b/packages/ui/src/types/guard.ts
new file mode 100644
index 000000000..b5135993c
--- /dev/null
+++ b/packages/ui/src/types/guard.ts
@@ -0,0 +1,12 @@
+import * as s from 'superstruct';
+
+export const bindSocialStateGuard = s.object({
+  relatedUser: s.optional(s.string()),
+});
+
+export const passcodeStateGuard = s.object({
+  email: s.optional(s.string()),
+  sms: s.optional(s.string()),
+});
+
+export const passcodeMethodGuard = s.union([s.literal('email'), s.literal('sms')]);
diff --git a/packages/ui/src/types/index.ts b/packages/ui/src/types/index.ts
index 3fded919a..3b48ff752 100644
--- a/packages/ui/src/types/index.ts
+++ b/packages/ui/src/types/index.ts
@@ -1,4 +1,5 @@
-import { SignInExperience, ConnectorMetadata } from '@logto/schemas';
+import { Language } from '@logto/phrases-ui';
+import { SignInExperience, ConnectorMetadata, AppearanceMode } from '@logto/schemas';
 
 export type UserFlow = 'sign-in' | 'register';
 export type SignInMethod = 'username' | 'email' | 'sms' | 'social';
@@ -34,3 +35,11 @@ export type SignInExperienceSettings = Omit<
 export enum TermsOfUseModalMessage {
   SHOW_DETAIL_MODAL = 'SHOW_DETAIL_MODAL',
 }
+
+export type PreviewConfig = {
+  signInExperience: SignInExperienceSettingsResponse;
+  language: Language;
+  mode: AppearanceMode.LightMode | AppearanceMode.DarkMode;
+  platform: Platform;
+  isNative: boolean;
+};
diff --git a/packages/ui/src/utils/country-code.ts b/packages/ui/src/utils/country-code.ts
index 12a048ecd..f0cf11cd6 100644
--- a/packages/ui/src/utils/country-code.ts
+++ b/packages/ui/src/utils/country-code.ts
@@ -18,6 +18,7 @@ export const countryCallingCodeMap: Record<string, CountryCode> = {
 export const isValidCountryCode = (countryCode: string): countryCode is CountryCode => {
   try {
     // Use getCountryCallingCode method to guard the input's value is in CountryCode union type, if type not match exceptions are expected
+    // eslint-disable-next-line no-restricted-syntax
     getCountryCallingCode(countryCode as CountryCode);
 
     return true;
diff --git a/packages/ui/src/utils/index.ts b/packages/ui/src/utils/index.ts
index 007cce7ca..1be203b06 100644
--- a/packages/ui/src/utils/index.ts
+++ b/packages/ui/src/utils/index.ts
@@ -26,16 +26,21 @@ export const getSearchParameters = (parameters: string | URLSearchParams, key: s
   return searchParameters.get(key) ?? undefined;
 };
 
-type Entries<T> = Array<
+export type Entries<T> = Array<
   {
     [K in keyof T]: [K, T[K]];
   }[keyof T]
 >;
 
-export const entries = <T>(object: T): Entries<T> => Object.entries(object) as Entries<T>;
+export const entries = <T extends Record<string, unknown>>(object: T): Entries<T> =>
+  // eslint-disable-next-line no-restricted-syntax
+  Object.entries(object) as Entries<T>;
 
-// eslint-disable-next-line @typescript-eslint/ban-types
-export const inOperator = <K extends string, T extends object>(
-  key: K,
+export const fromEntries = <T extends Record<string, unknown>>(entries: Entries<T>) =>
+  // eslint-disable-next-line no-restricted-syntax
+  Object.fromEntries(entries) as T;
+
+export const isKeyOf = <T extends Record<string, unknown>>(
+  key: string | number | symbol,
   object: T
-): object is T & Record<K, unknown> => key in object;
+): key is keyof T => key in object;
diff --git a/packages/ui/src/utils/sign-in-experience.ts b/packages/ui/src/utils/sign-in-experience.ts
index 6c828c7f9..4f0f4b8ec 100644
--- a/packages/ui/src/utils/sign-in-experience.ts
+++ b/packages/ui/src/utils/sign-in-experience.ts
@@ -9,10 +9,12 @@ import { getSignInExperience } from '@/apis/settings';
 import { SignInMethod, SignInExperienceSettingsResponse, SignInExperienceSettings } from '@/types';
 import { filterSocialConnectors } from '@/utils/social-connectors';
 
+import { entries } from '.';
+
 export const getPrimarySignInMethod = (signInMethods: SignInMethods) => {
-  for (const [key, value] of Object.entries(signInMethods)) {
+  for (const [key, value] of entries(signInMethods)) {
     if (value === 'primary') {
-      return key as keyof SignInMethods;
+      return key;
     }
   }
 
@@ -20,9 +22,9 @@ export const getPrimarySignInMethod = (signInMethods: SignInMethods) => {
 };
 
 export const getSecondarySignInMethods = (signInMethods: SignInMethods) =>
-  Object.entries(signInMethods).reduce<SignInMethod[]>((methods, [key, value]) => {
+  entries(signInMethods).reduce<SignInMethod[]>((methods, [key, value]) => {
     if (value === 'secondary') {
-      return [...methods, key as SignInMethod];
+      return [...methods, key];
     }
 
     return methods;
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 4f9255e24..5812b18dc 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -1225,6 +1225,7 @@ importers:
       react-string-replace: ^1.0.0
       react-timer-hook: ^3.0.5
       stylelint: ^14.8.2
+      superstruct: ^0.16.0
       typescript: ^4.6.2
       use-debounced-loader: ^0.1.1
     dependencies:
@@ -1277,6 +1278,7 @@ importers:
       react-string-replace: 1.0.0
       react-timer-hook: 3.0.5_sfoxds7t5ydpegc3knd667wn6m
       stylelint: 14.8.2
+      superstruct: 0.16.0
       typescript: 4.6.2
       use-debounced-loader: 0.1.1_react@17.0.2